In a large mixing bowl, combine the pork belly, pork loin, liver, port, garlic, juniper berries, peppercorns, dried mixed herbs and a little salt. Mix well with your hands, breaking the mixture up as much as possible. Cover and leave to marinate for 1 hour.
After 1 hour, preheat the oven to 150°C.
Spoon the meat mixture into a 2lb terrine bowl, spreading it out evenly with the back of a spoon. Half-fill a roasting tray with boiling water then sit the terrine bowl in the water. Bake in the oven for 90-120 minutes until the internal temperature of the pâté reaches 65°C. Use a meat thermometer to test the internal temperature. Remove once is reaches 65°C, then leave it to cool to one side.
As it is cooling, you can prepare the aspic jelly. Place all the ingredients for the jelly in a heavy-based saucepan and set over a moderate heat. Whisk until the gelatine softens, then continue to whisk as you bring the mixture to the boil. Simmer for a few minutes, then pour the liquid very carefully through the crusty layer that has formed on top through a muslin lined sieve into a clean bowl. Cover and leave the mixture to cool to one side.
Once cool, pour on top of the cooled pate and chill the dish for a few hours until the jelly has set. Remove 5-10 minutes before serving.
For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home.